<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        var time = 5;

        function clock() {
            document.body.innerHTML = "";
            document.write("倒计时：" + time);
            time -= 1;
            if (time == -1) jump();
        }

        window.setInterval("clock()", 1000);

        function jump() {
            window.location.href = "https://www.baidu.com";
        }
    </script>
</head>
<body>

</body>
</html>